Droplet ejection devices are used for a variety of purposes, most commonly for printing images on various media. Droplet ejection devices are often referred to as ink jets or ink jet printers. Drop-on-demand droplet ejection devices are used in many applications because of their flexibility and economy. Drop-on-demand devices eject one or more droplets in response to a specific signal, usually an electrical waveform that may include a single pulse or multiple pulses. Different portions of a multi-pulse waveform can be selectively activated to produce the droplets.
Droplet ejection devices typically include a fluid path from a fluid supply to a nozzle path. The nozzle path terminates in a nozzle opening from which droplets are ejected. Inkjet print heads exhibit highly coupled electrical, mechanical, and fluidic behavior and are sensitive to non-uniformities that arise from manufacturing variations, cross-talk, loading, and natural frequency response. Thus, non-uniformities in drop velocity and mass distribution exist across a print head having a large number of closely spaced nozzles. It is desirable to lower the impact of these non-uniformities on output pattern quality. Previous approaches include tightening manufacturing tolerances or additional electronics such as amplifiers and switches to drive various nozzles using separate waveforms to compensate for variations. However, these previous approaches are more expensive to implement because of the additional electronics and also require more time for separate waveforms.